Display devices such as a liquid crystal display device and an organic electroluminescent (EL) display device include various components on an insulating substrate, such as gate lines and source lines used for driving pixels, and switching elements. During the manufacturing process of such a display device, the insulating substrate, lines and electrodes in the electrically floating state tend to become electrostatically charged by, for example, contact, friction, and exfoliation between the insulating substrate and various manufacturing apparatuses and conveying mechanisms or by a plasma treatment such as plasma chemical vapor deposition (CVD) and plasma etching. The electrostatic energy may sometimes cause electrostatic discharge (ESD) during the manufacturing process which damages the components having capacitance such as switching elements. Hereinafter, such a phenomenon is referred to as electrostatic destruction.
Due to a strong demand for high-definition display devices, miniaturization of switching elements and lines is in progress. A miniaturized switching element has a small capacitance which easily leads to electrostatic destruction. This must be dealt with for increased productivity.